A paging system is used to send electronic notices, called pages, to system subscribers to inform them that they have been called by other individuals. A typical paging system includes a paging terminal and one or more paging stations. The paging terminal is connected to the publicly switched telephone network and is configured to receive incoming telephone calls from individuals interested in accessing the system subscribers. In response to receiving a call, the paging terminal creates a block of information, a page, for the subscriber. The page is forwarded to the paging stations, which then broadcast the page. System subscribers carry pagers, which are miniaturized radio receivers. When a pager receives a page for the subscriber to whom the pager has been assigned, the pager actuates an internal audio annunciator and/or display to inform the subscriber of the page and its contents.
A paging system is typically configured so that a system subscriber can select the class or type of paging service that he wants to receive. The basic service many paging systems offer is to simply broadcast a page to the subscriber to inform the subscriber that he has been called. Once the subscriber has received this page, which is indicated by a beeping tone and/or a flashing light, the subscriber must access the paging terminal to find the identity, or at least the phone number, of the calling party. Many paging systems offer subscribers an intermediate level of service, which allows the subscribers to receive a short numeric or alphanumeric message as part of the page. This message is presented on a small display integral with the pager. Some paging systems offer an even more advanced level of service that allows a caller to leave a message that will be transmitted to the subscriber. A pager carried by a subscriber using this service includes a small audio signal-processing circuit that, upon receipt of the page, plays the message on a small speaker also integral with the pager. Many paging systems also include some type of voice-mail storage capability that allows a caller to record a message that the subscriber can retrieve at his convenience. Some paging systems are even configured to allow system subscribers to make customized greetings that instruct callers how to make a page and/or leave a voice-mail message. Many paging systems are configured to allow a subscriber to select the particular services that form his/her package of paging services.
While paging systems have proved a useful means for contacting individuals who are away from their telephones, they suffer a serious limitation. Few paging systems offer any means for actually connecting a subscriber to a caller. Consequently, many individuals prefer to subscribe to cellular telephone systems. These systems provide subscribers with cordless portable telephones. These systems also include a number of fixed mobile telephone switching offices (MTSOs). Equipment in the MTSOs tracks the cellular telephones and provides a radio link between the callers and cellular telephone subscribers. A disadvantage of cellular telephone systems, however, is that there are limited radio frequencies over which cellular service can be offered. Consequently, cellular telephone systems can be used to offer communications services for only a limited number of subscribers. Another disadvantage of cellular telephone systems is that, in order for a subscriber to use the subscriber's portable telephone, the subscriber must be in an area that is served by the subscriber's cellular service provider. Many cellular providers offer service through only a limited service area. Once a subscriber leaves the service area, the subscriber is no longer able to receive incoming calls.